// ============================================
// Pointers (p. 4)
int* p1 = 0;
cout << sizeof(p1) << endl; // 8
double* p2 = 0;
cout << sizeof(p2) << endl; // 8
// ============================================
// Pointers (p. 12)
int a = 10;
int* p1 = &a;
cout << "value of a = " << a << endl;
cout << "value of p1 = " << p1 << endl;
cout << "address of a = " << &a << endl;
cout << "address of p1 = " << &p1 << endl;
cout << "value of the variable pointed by p1 = " << *p1 << endl;
// ============================================
// Pointers (p. 15)
// left
int a = 10;
int* ptr = &a;
cout << *ptr; // ?
*ptr = 5;
cout << a; // ?
a = 18;
cout << *ptr; // ?
// right
int a = 10;
int* ptr1;
int* ptr2;
ptr1 = ptr2 = &a;
cout << *ptr1; // ?
*ptr2 = 5;
cout << *ptr1; // ?
(*ptr1)++;
cout << a; // ?
// ============================================
// Pointers (p. 16)
int* ptr;
cout << *ptr; // ?
int* p2 = nullptr;
cout << "value of p2 = " << p2 << "\n";
cout << "address of p2 = " << &p2 << "\n";
cout << "the variable pointed by p2 = " << *p2 << "\n";
// ============================================
// Pointers (p. 17)
#include <iostream>
using namespace std;
int main()
{
int* ptrArray[10000];
for(int i = 0; i < 10000; i++)
cout << i << " " << *ptrArray[i] << "\n";
return 0;
}
// ============================================
// Pointers (p. 22)
int c = 10;
int& d = c; // declare d as c��s reference
d = 20;
cout << c << endl; // 20
// ============================================
// Pointers (p. 23)
void swap(int& x, int& y);
int main()
{
int a = 10, b = 20;
cout << a << " " << b << "\n";
cout << &a << "\n";
swap(a, b);
cout << a << " " << b << "\n";
}
void swap(int& x, int& y)
{
cout << &x << "\n";
int temp = x;
x = y;
y = temp;
}
// ============================================
// Pointers (p. 25)
void swap(int* ptrA, int* ptrB)
{
int temp = *ptrA;
*ptrA = *ptrB;
*ptrB = temp;
}
// ============================================
// Pointers (p. 31)
void swap(int* ptrA, int* ptrB)
{
int* temp = ptrA;
ptrA = ptrB;
ptrB = temp;
}
// ============================================
// Pointers (p. 57)
#include <iostream>
using namespace std;
int main()
{
for(int i = 0; ; i++)
{
int* ptr = new int[100000];
cout << i << "\n";
// delete [] ptr;
}
return 0;
}
// ============================================
// Pointers (p. 61)
int main()
{
int r = 3;
int** array = new int*[r];
for(int i = 0; i < r; i++)
{
array[i] = new int[i + 1];
for(int j = 0; j <= i; j++)
array[i][j] = j + 1;
}
print(array, r); // later
// some delete statements
return 0;
}
// ============================================
// Pointers (p. 71)
void print(int** arr, int r)
{
for(int i = 0; i < r; i++)
{
for(int j = 0; j <= i; j++)
cout << arr[i][j] << " ";
cout << "\n";
}
}
// ============================================
// Pointers (p. 72)
void print1D(int* arr, int n)
{
for(int i = 0; i < n; i++)
cout << arr[i] << " ";
cout << "\n";
}
int print(int** arr, int r)
{
for(int i = 0; i < r; i++)
{
print1D(arr[i], i + 1);
}
}
// ============================================
// Pointers (p. 75)
int a = 10;
int* ptr = &a;
cout << ptr++;
// just an address
// we don't know what's here
cout << *ptr;
// dangerous!
// ============================================
// Pointers (p. 76)
double a[3] = {10.5, 11.5, 12.5};
double* b = &a[0];
cout << *b << " " << b << endl; // 10.5
b = b + 2;
cout << *b << " " << b << endl; // 12.5
b--;
cout << *b << " " << b << endl; // 11.5
// ============================================
// Pointers (p. 77)
double a[3] = {10.5, 11.5, 12.5};
double* b = &a[0];
double* c = &a[2];
cout << c - b << endl; // 2, not 16!
// ============================================
// Pointers (p. 78)
int x[3] = {1, 2, 3};
for(int i = 0; i < 3; i++)
cout << *(x + i) << " "; // 1 2 3
for(int i = 0; i < 3; i++)
cout << *(x++) << " "; // 1 2 3
for(int i = 0; i < 3; i++)
cout << *(x + i) << " "; // unpredictable
// ============================================
// Pointers (p. 79)
int x[3] = {1, 2, 3};
for(int i = 0; i < 3; i++)
cout << x[i] << " "; // x[i] == *(x + i)
for(int i = 0; i < 3; i++)
cout << *(x + i) << " "; // 1 2 3
int x[3] = {1, 2, 3};
for(int i = 0; i < 3; i++)
cout << *(x++) << " "; // error!
// ============================================
// Pointers (p. 80)
#include <iostream>
using namespace std;
int main()
{
int a[5] = {0};
for(int i = 0; i < 5; i++)
cin >> a[i];
int* p = a;
for(int i = 0; i < 5; i++) {
*p += 3;
p++;
}
for(int i = 0; i < 5; i++)
cout << a[i] << " ";
return 0;
}
// ============================================
// Pointers (p. 82)
void insertionSort(int array[], const int n)
{
if(n > 1)
{
insertionSort(array + 1, n - 1);
int num1 = array[0];
int i = 1;
for(; i < n; i++)
{
if(array[i] < num1)
array[i - 1] = array[i];
else
break;
}
array[i - 1] = num1;
}
}
// ============================================
// Pointers (p. 83)
#include <iostream>
using namespace std;
int* firstNeg(int a[], const int n) {
for(int i = 0; i < n; i++) {
if(a[i] < 0)
return &a[i];
} // what if a[i] >= 0 for all i?
}
int main()
{
int a[5] = {0};
for(int i = 0; i < 5; i++)
cin >> a[i];
int* p = firstNeg(a, 5);
cout << *p << " " << p - a << "\n";
return 0; // what is p - a?
}
// ============================================
// Pointers (p. 84)
#include <iostream>
using namespace std;
int* firstNeg(int a[], const int n) {
for(int i = 0; i < n; i++) {
if(a[i] < 0)
return &a[i];
}
return nullptr;
}
int main()
{
int a[5] = {0};
for(int i = 0; i < 5; i++)
cin >> a[i];
int* p = firstNeg(a, 5);
if(p != nullptr)
cout << *p << " " << p - a << "\n";
return 0;
}
// ============================================
// Pointers (p. 85)
#include <iostream>
using namespace std;
int* firstNeg(int a[], const int n) {
for(int i = 0; i < n; i++) {
if(a[i] < 0)
return &a[i];
}
return nullptr;
}
int main()
{
int a[5] = {0};
for(int i = 0; i < 5; i++)
cin >> a[i];
int* p = firstNeg(a, 5);
if(p != nullptr)
*p = -1 * *p; // *p at the LHS of =
return 0;
}
// ============================================
// Pointers (p. 86)
#include <iostream>
using namespace std;
const int* firstNeg
(const int a[], const int n) {
for(int i = 0; i < n; i++) {
if(a[i] < 0)
return &a[i];
}
return nullptr;
}
int main()
{
int a[5] = {0};
for(int i = 0; i < 5; i++)
cin >> a[i];
const int* p = firstNeg(a, 5);
if(p != nullptr)
cout << *p << "\n"; // OK
return 0;
}
